1. Field
This document relates to a liquid crystal display that can modulate gate pulses with minimum clocks.
2. Discussion of the Related Art
Various types of flat panel displays having reduced weight and volume, which are drawbacks of cathode ray tubes (CTRs), are being developed. These flat panel displays include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and electroluminescence devices (ELs).
Applications of liquid crystal displays are gradually expanding thanks to their lightweight, thin, and low power consuming characteristics. Liquid crystal displays are employed in portable computers such as laptop computers, office equipment, audio/video apparatuses, indoor/outdoor advertising devices, etc. A liquid crystal display displays an image by controlling electric fields applied across liquid crystal cells to modulate light emitted from a backlight unit.
A voltage applied across liquid crystal cells in an active matrix type LCD is affected by a kickback voltage (or feed through voltage, ΔVp) that occurs due to parasitic capacitance of a TFT (Thin Film Transistor). The kickback voltage (ΔVp) is as shown in Equation 1:
                              Δ          ⁢                                          ⁢          Vp                =                              Cgd                          Clc              +              Cst              +              Cgd                                ⁢                      (                          Von              -              Voff                        )                                              [                  Equation          ⁢                                          ⁢          1                ]            
Here, ‘Cgd’ refers to parasitic capacitance between the gate terminal of a TFT connected to a gate line and the drain terminal of a TFT connected to a pixel electrode of a liquid crystal cell, and ‘Von-Voff’ refers to a difference between a gate-high voltage and a gate-low voltage of a gate pulse applied to a gate line.
The kickback voltage varies the voltage applied to a pixel electrode of a liquid crystal cell, causing flickering and image sticking in a displayed image.